WO2003097314A1

WO2003097314A1 - Method of manufacturing honeycomb structural body

Info

Publication number: WO2003097314A1
Application number: PCT/JP2003/006201
Authority: WO
Inventors: Shigeki Kato; Mitsuru Miyamoto
Original assignee: Ngk Insulators, Ltd.
Priority date: 2002-05-20
Filing date: 2003-05-19
Publication date: 2003-11-27
Also published as: JP2003334810A; DE60323485D1; EP1508416A1; EP1508416B1; AU2003242322A1; US20040198599A1; EP1508416A4; ZA200401191B; JP4112899B2; CN1307030C; CN1556741A

Abstract

A method of manufacturing a ceramic honeycomb structural body (1) with a plurality of cells, comprising the steps of applying a mask (11) to a part of the cells at the end face thereof, immersing the end face covered by the mask (11) in slurry (10) containing at least ceramic powder to pressingly fill the slurry (10) into the remaining cells so as to form a sealed part (2), and drying the sealed part (2), characterized in that the sealed part (2) is dried by a heat conductive means (12), whereby the honeycomb structural body (1) having the sealed remaining cells can be provided.

Description

Specification

Manufacturing method of 82 cam structure

The present invention relates to a method for manufacturing a honeycomb structure in which some of a large number of cells are plugged, which is preferably used as, for example, a dust collection filter. Background art

In recent years, in various fields such as chemical, electric power, steel and industrial waste treatment, environmental protection such as pollution prevention, heat collection as a filter for dust collection used for applications such as product recovery from high temperature gas, A ceramic honeycomb structure having excellent corrosion resistance is used. For example, a ceramic honeycomb structure (hereinafter simply referred to as “honeycomb”) is used as a dust-collecting filter used in a high-temperature, corrosive gas atmosphere such as a diesel particulate filter (DPF) that collects particulates discharged from a diesel engine. The structure is sometimes referred to as “structure.”) Is preferably used.

The honeycomb structure used as a dust collection filter as described above is required to have a structure with low pressure loss and high collection efficiency. Therefore, a honeycomb structure in which some of the cells are plugged is used. For example, as shown in FIG. 2, in the honeycomb structure 21 having a structure in which the inlet-side end face B and the outlet-side end face C of a large number of cells 23 of the honeycomb structure are alternately plugged by the plugging portions 22. is, when introduced into the cell 2 3 gas to be treated G _t from the inlet end face B, while the dust or Patikiyure one bets are trapped in the partition walls 2 4, cells 2 adjacent through the partition wall 2 4 porous The treated gas G ₂ flowing into 3 is discharged from the outlet side end face C.

In the above honeycomb structure, a part of cells is masked at an end face of a cylindrical ceramic honeycomb structure having a plurality of cells serving as a fluid flow path, and the masked end face of the ceramic honeycomb structure is ceramic powder. By immersing the slurry in a slurry containing a dispersion medium or the like, the slurry is pressed into the remaining cells to form a plugged portion, and the plugged portion is dried to produce the slurry. And, conventionally, Drying of the plugged portion has been performed by hot-air drying using a hot-air drying furnace. However, the honeycomb structure manufactured by the above-described manufacturing method has a problem that a defect occurs in a plugging portion. FIG. 3 is a schematic enlarged cross-sectional view near the entrance end face B of the honeycomb structure 21. The plugging portion 22 originally to be formed as shown in (i) of FIG. As shown in Fig. 3 (ii), sink marks 26 occur, and in extreme cases, a hole 27 penetrating the plugging part 22 opens as shown in Fig. 3 (iii). There was.

If sink marks 26 occur, the reliability of the plugged portion 22 may be reduced, or if a hole 27 penetrating the plugged portion 22 is opened. When used as a filter for dust collection, dust and particulates leak from the holes 27 and do not function as a filter. Accordingly, conventionally, as shown in FIG. Problems were avoided. However, when the plugging depth d is increased, the surface area of the partition wall 24 for dividing the cell 22, that is, the filtration area is undesirably reduced. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and an object of the present invention is to produce a sink mark defect in a plugged portion or to penetrate a plugged portion. An object of the present invention is to provide a method for manufacturing a honeycomb structure that can effectively prevent a situation in which a hole is formed.

The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems. As a result, instead of drying the plugged portion with a heat convection means such as a conventional hot air drying furnace, the plugged portion is dried by a heat conduction means. The inventors have found that the above objects can be achieved, and have completed the present invention. That is, the present invention provides the following method for manufacturing an 82 cam structure.

(1) Some cells are masked at the end face of a cylindrical ceramic honeycomb structure having a plurality of cells serving as a fluid flow path, and the masked end face of the ceramic honeycomb structure is formed of at least ceramic powder and a dispersion medium. Containing a binder and a binder By immersing the slurry into the remaining cells, the slurry is pressed into the remaining cells to form plugging portions, and the plugging portions are dried to obtain a honeycomb structure in which the remaining cells are plugged. A method for manufacturing a two-cam structure, comprising drying the plugged portion by means of heat conduction.

(2) The method for manufacturing an 82 cam structure according to (1), wherein the heat conducting means is an electric heating plate.

(3) The method of manufacturing an 82 cam structure according to (1) or (2), wherein the thickness of the mask is 0.03 to 0.5 mm.

(4) The method for producing a honeycomb structure according to any one of (1) to (3), wherein the binder contained in the slurry is a thermogel-curable binder.

(5) The method for manufacturing a honeycomb structure according to any one of (1) to (4), wherein the viscosity of the slurry is 50 to 500 dPa * s. BRIEF DESCRIPTION OF THE FIGURES

1 (a) and 1 (b) are step diagrams showing one embodiment of a method for manufacturing a honeycomb structure according to the present invention, and FIG. 1 (a) shows a step of forming a plugged portion. FIG. 1 (b) is a schematic view showing a step of drying the plugged portion.

FIG. 2 is a schematic view showing the structure of a general honeycomb structure.

FIG. 3 is a schematic enlarged cross-sectional view near the inlet-side end face of the honeycomb structure.

FIG. 4 is a schematic enlarged cross-sectional view near the inlet-side end face of the honeycomb structure. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a method for manufacturing a honeycomb structure of the present invention will be specifically described with reference to the drawings.

In developing the method for manufacturing a honeycomb structure according to the present invention, the inventor first examined the reason why a sink defect occurs in a plugged portion or a hole penetrating the plugged portion is opened. As a result, when the plugged portion is dried by a heat convection means such as a hot-air drying furnace as in the past, sink marks are generated in the plugged portion due to the low drying speed. Or a hole that penetrates the sealing part is found Was.

More specifically, when the plugging portion is dried by a heat convection means such as a hot air drying oven, the drying speed is relatively slow, so that the outside of the plugging portion (the 82 cam structure) is used. From the end face of the body), drying (volatilization of water in the slurry forming the plugging portion) is performed gradually, and with this, the water in the slurry passes through the plugging portion from the inside to the outside (honeycomb). (The end face of the structure). At this time, of the ceramic particles in the slurry, the particles that are in contact with the inner wall of the cell remain at that part due to the anchor effect, while the particles that are not in contact with the inner wall of the cell are in the plugged portion together with moisture. Gradually moves from the inside to the outside (the end face of the honeycomb structure). Due to this phenomenon, sink marks are generated in the plugged portion or a hole penetrating the plugged portion is opened.

As described above, since the sink mark is generated in the plugged portion or the hole penetrating the plugged portion is caused by the low drying speed, such a situation is prevented. In order to do this, it is necessary to increase the drying speed.

Therefore, in the present invention, the plugged portion is not dried by a heat convection means such as a conventional hot air drying furnace, but is dried by a heat conduction means. In this case, the drying speed is high, and the entire plugging portion is immediately dried (water in the slurry forming the plugging portion is volatilized), so that the water in the slurry passes through the plugging portion inside the plugging portion. The phenomenon of gradually moving from the outside to the outside (the end face of the 82 cam structure) does not occur. Therefore, the ceramic particles that are not in contact with the inner wall of the cell in the slurry gradually move from the inside to the outside (the end face side of the honeycomb structure) in the plugging portion together with the moisture. Therefore, it is possible to effectively prevent a sink mark defect from being generated in the plugged portion or a hole that penetrates the plugged portion being opened.

In addition, in the manufacturing method of the present invention, since sink marks and the like do not occur, the plugging depth, which was conventionally deeper than necessary, about 10 mm, can be reduced to about 1 to 5 mm. Therefore, the plugging can be performed effectively without reducing the surface area of the partition for separating the cells, that is, the filtration area of the filter.

The ceramic honeycomb structure to be subjected to the manufacturing method of the present invention serves as a fluid flow path. 1 is a ceramic honeycomb structure having a plurality of cells. The material is not particularly limited as long as it is ceramic, and examples thereof include cordierite. The method for manufacturing the ceramic 82 cam structure is not particularly limited, but a method of extruding a clay having an appropriate viscosity using a die having a desired cell shape, a partition wall thickness, and a cell density, drying the clay, and the like. Can be suitably used.

In the manufacturing method of the present invention, first, some cells are masked on the end face of the ceramic honeycomb structure (hereinafter, may be simply referred to as “honeycomb structure”).

The method of the mask is not particularly limited, and examples thereof include a method in which an adhesive film is attached to the entire end face of the honeycomb structure and a part of the adhesive film is perforated. More specifically, it is preferable to use a method in which a pressure-sensitive adhesive film is attached to the entire end face of the honeycomb structure and a hole is formed with a laser only in a portion corresponding to a cell where a plugging portion is to be formed. it can.

The thickness of the mask is preferably in the range of 0.3 to 0.5 mm. If the thickness of the mask is too large, the distance between the plugging portion and the heat conducting means (for example, an electric heating plate, etc.) becomes too long, and a gap may be formed between the two, so that the heat transfer speed becomes low, and the sink mark defect occurs Is more likely to occur. On the other hand, if the thickness of the mask is too thin, the strength of the mask is reduced, so that it is difficult to attach the mask to the end face of the honeycomb structure, and the workability is reduced. As the adhesive film, a film in which an adhesive is applied to one surface of a film made of polyethylene or the like can be suitably used. At this time, the adhesive film may be appropriately selected from commercially available ones having the above thickness range. The thickness may be controlled to a desired thickness by laminating and attaching a plurality of commercially available adhesive films.

Next, the masked end face of the honeycomb structure is immersed in a slurry containing at least a ceramic powder, a dispersion medium, and a binder to press-fit the slurry into the remaining cells to form a plugged portion.

For example, with the masked end face of the honeycomb structure facing down, the honeycomb structure is pushed into a slurry-filled press-fitting vessel while applying an appropriate pressure, so that the masked end face of the honeycomb structure is formed. Is immersed in the slurry. The slurry can be prepared by mixing at least a ceramic powder, a dispersion medium (for example, water, etc.) and a binder. Further, if necessary, additives such as a deflocculant may be added. Although the material of the ceramic powder is not particularly limited, for example, cordierite or the like can be suitably used. As the binder, a resin such as polyvinyl alcohol (hereinafter referred to as “PVA”) can be used, but a thermogel-curable binder having a property of gelling by heating should be used. Is more preferred. The thermogel-curable binder gels (hardens) by heating and binds the ceramic particles, so that only the water in the slurry can be volatilized, which is effective in preventing sink marks. As the thermogel-curable binder, methylcellulose can be suitably used.

At this time, the viscosity of the slurry is preferably 50 to 500 dPa, s, and more preferably 50 to 200 dPa's. If the viscosity of the slurry is too low, the ceramic particles tend to move, which is not preferable in that sink marks are likely to occur. On the other hand, if the viscosity of the slurry is too high, the flow resistance between the slurry and the cell wall increases, and the difference in the injection speed of the slurry between the vicinity of the cell wall and the center of the cell increases. Specifically, the plugging depth in the vicinity of the cell wall is smaller than that in the central part of the cell, which is not preferable in that the contact area between the honeycomb structure and the plugging material is reduced. The viscosity of the slurry can be adjusted by, for example, the ratio between the ceramic powder and the dispersion medium (for example, water or the like) or the amount of the deflocculant.

Finally, the plugged portion is dried by heat conduction means to obtain a honeycomb structure in which the remaining cells are plugged.

"By means of heat conduction" means, instead of drying by means of heat convection such as a conventional hot air drying oven (that is, drying by the flow of a heating medium such as hot air), means of heat conduction such as heating and drying. It means drying by directly contacting the plugging part with the garment. As the heat conducting means, for example, an electric heating plate or the like can be suitably used. Drying by means of heat conduction speeds up the drying speed and instantaneous drying (volatilization of water in the slurry forming the plugging portion) in the entire plugging portion. It is possible to effectively prevent a situation in which a hole is generated or a hole penetrating the plugging portion is opened. As described above, by drying the plugged portion, the honeycomb structure in which the remaining cells are plugged, for example, in the case of cordierite, usually at about 144 ° C. The final product is obtained by firing for about 5 hours.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples.

As the honeycomb structure in this example, a cylindrical structure made of cordierite and having an outer diameter of 16 6πιπιφ and a length of 20 O mm was used. The cell had a square cell shape, a partition wall thickness of 300 / m, and a cell density of 300 cells per square inch. The honeycomb structure is extruded using a die having the above-mentioned cell shape, partition wall thickness, and cell density by adjusting the clay to an appropriate viscosity, dried, and cut at both end surfaces to obtain a smooth surface. Manufactured.

First, some cells were masked on the end face of the honeycomb structure. The mask was formed by attaching an adhesive film to the entire end face of the honeycomb structure, and then punching holes only with a laser at a portion corresponding to a cell where a plugging portion is to be formed. As the adhesive film, a commercially available adhesive film (a film in which an adhesive was applied to one surface of a polyethylene film) was used.

By immersing the masked end surface of the honeycomb structure in the slurry, the slurry was pressed into the remaining cells to form plugging portions. Specifically, as shown in FIG. 1 (a), 50 g of the slurry 10 is put into the press-fitting container 9 so as to have a depth of 5 mm (this depth corresponds to the plugging depth). And, the liquid surface is stretched so as to be smooth, and the end face with the mask 11 of the honeycomb structure 1 is placed downward in the press-fitting container 9 (set vertically to the liquid surface). The end face of the honeycomb structure 1 on which the mask 11 was applied was immersed in the slurry 10 by applying pressure while applying a pressure of 2 kg Z cm ² . Finally, the plugged portion was dried to obtain a honeycomb structure. In the following Examples and Comparative Examples, the effects were confirmed by appropriately changing the thickness of the adhesive film used for the mask, the viscosity of the slurry, the drying means, and the drying method among the above-mentioned manufacturing methods. .

(Comparative Example 1)

As a mask method, a method using an adhesive film was employed. Sticky filler The thickness of the lum was 0.05 mm. The slurry used for plugging is cordierite powder as a ceramic powder, methylcellulose which is a thermogel-curable binder as a binder, and a special carboxylic acid type polymer surfactant as a deflocculant (trade name: POLY (Trade name: 530, manufactured by Kao Corporation) were mixed in the ratio shown in Table 1, and water was added as a dispersion medium, followed by mixing for 30 minutes. The slurry viscosity was 90 dPa · s. Drying was performed using a hot-air drying oven at a set temperature of 250 ° C for 5 minutes.

Slurry-mixing ratio used for mask Slurry-viscosity Drying means Drying state Thickness of adhesive film Kosiella] Peptizer

(mm) (parts by mass) (parts by mass) (parts by mass) (dPa's)

Comparative Example 1 0.05 100 Methylcellulose 0.3 0.4 90 Hot-air drying oven D-x Example 1 0.05 100 Methylcellulose 0.3 0.490 Electric heating plate A- © Example 2 0.5 100 Methylcellulose 0.3 0.4 90 Electric heating plate A- Example 3 1 100 Methylcellulose 0.3 0.4 90 Electric heating. Rate B-0 Example 4 0.05 100 Methyl cell D-source 0.3 0.420 Electric heating. Rate B 例 Example 5 0.05 100 Methylcellulose 0.3 0.4 50 Electric heating Λ-A-§ Example 6 0.05 100 Methylcellulose 0.3 0.4 200 Electric heating. Rate A- © Example 7 0.05 100 Methylcellulose 0.3 0.4 500 Electric heating W A-§ Example 8 0.05 100 Methylcellulose 0.3 0.4 2000 Electric heating. Rate-O Example 9 0.05 100 PVA 0.3 (solid content) 0.4 100 Rate C-0

(Example 1)

As a mask method, a method using an adhesive film was employed. The thickness of the adhesive film and the slurry used for plugging were the same as in Comparative Example 1, and as shown in Fig. 1 (b), a heat conducting means 12 (electric heating plate) was used as the drying means. Drying was performed for 5 minutes by bringing the sealing portion 2 of the 82 cam structure 1 into direct contact with the heat conducting means 12 (electric heating plate) at a set temperature of 250 ° C.

(Examples 2 and 3)

As a mask method, a method using an adhesive film was employed. As the adhesive film, one having a thickness of 0.5 mm was used, and one sheet of the adhesive film (thickness: 5 mm) was used as Example 2 and two sheets were laminated and attached. The product (thickness l mm) was used as Example 3. The slurry used for plugging, the drying means, and the drying method were the same as in Example 1.

(Examples 4 to 8)

As a mask method, a method using an adhesive film was employed. The thickness of the adhesive film, the drying means and the drying method are the same as in Example 1. The slurry used for plugging is cordierite powder as a ceramic powder, and methylcellulose as a thermogel-curable binder as a binder. As a deflocculant, a special carboxylic acid type polymer surfactant (trade name: BOYS 530, manufactured by Kao Corporation) is mixed in the ratio shown in Table 1, water is added as a dispersion medium, and the amount of water is adjusted as appropriate. The one prepared by adjusting the viscosity and mixing for 30 minutes was used. The slurry viscosity was 20 dPas (Example 4), 50 dPas (Example 5), 200 dPas (Example 6), 500 dP a · s (Example 7) and 2000 dPas · s (Example 8).

(Example 9)

As a mask method, a method using an adhesive film was employed. The thickness of the adhesive film, drying method and drying method were the same as in Example 1, and the slurry used for plugging was prepared in the same manner as in Example 1 except that PVA was used instead of methyl cellulose as a binder. What was done was used. The slurry viscosity was 100 dPa · s.

(Evaluation) After the drying was completed, the state of the plugged portion was evaluated by observing the results. Table 1 shows the results. FIG. 4 is a schematic enlarged cross-sectional view near the inlet-side end face B of the honeycomb structure 21. FIGS. 4A and 4B show a state in which no sink mark is generated as shown in (i) of FIG. As shown in Fig. 4 (ii), a state in which dents 28 slightly occurred but there was no problem in practice B, and as shown in Fig. 4 (iii), no sink mark was generated, but the plugged portion The state in which the end of 22 was rounded and the contact area with the cell 23 was reduced was denoted as C, and the state in which sink marks 26 were generated as shown in (iv) of FIG. 4 was denoted as D. In addition, ◎ indicates a very good state, Δ indicates a good state, and X indicates a bad state.

(Result)

As shown in Table 1, according to the manufacturing methods of Examples 1 to 9, it is possible to effectively prevent the occurrence of sink marks in the plugged portion or the opening of a hole penetrating the plugged portion. did it. On the other hand, in the manufacturing method of Comparative Example 1, sink marks were generated in the plugged portion, and the plug was in a defective state. Industrial applicability ''

As described above, in the method for manufacturing the 82 cam structure of the present invention, since the plugged portion is dried by the heat conducting means, a sink mark is generated in the plugged portion, or the plugged portion is dried. A situation in which a hole penetrating the sealing portion is opened can be effectively prevented.

Claims

The scope of the claims

1. Some cells are masked at the end face of the ceramic 82 cam structure having a plurality of cells serving as a fluid flow path, and the masked end face of the ceramic honeycomb structure is made of at least ceramic powder and a dispersion medium. By immersing the slurry in a slurry containing a binder, the slurry is pressed into the remaining cells to form a plugged portion, and the plugged portion is dried to form a honeycomb in which the remaining cells are plugged. A method of manufacturing an eighty-cam structure to obtain a structure,

A method for manufacturing an eighty-cam structure, wherein the plugged portion is dried by a heat conducting means.

2. The method for manufacturing a honeycomb structure according to claim 1, wherein the heat conducting means is an electric heating plate.

3. The method for manufacturing a honeycomb structure according to claim 1, wherein the thickness of the mask is 0.03 to 0.5 mm.

4. The method for manufacturing a honeycomb structure according to any one of claims 1 to 3, wherein the binder contained in the slurry is a thermogel-curable binder.

5. The method for producing an 82-cam structure according to any one of claims 1 to 4, wherein the viscosity of the slurry is 50 to 500 dPa · s.